Conventionally, a water supply apparatus which installs a power generating unit in a midst of a flow passage for supplying water to an indoor facility has been popularly used. In such a water supply apparatus, the power generating unit generates an electric power by making use of a water flow in the inside of the flow passage and various electronic equipment such as sensors and switches which are mounted inside or outside the water supply apparatus are driven using the generated electricity.
For example, in an automatic water supply apparatus disclosed in Japanese Patent Laid-open Publication Sho59(1984)-217074, a flow passage is formed in the inside of an apparatus body, a rotary shaft whose rotating axis extends in the direction orthogonal to the direction of a water flow is rotatably provided in a midst of the flow passage, and blades are formed on an outer periphery of the rotary shaft in a state that the blades extend in the radial direction.
Further, the rotary shaft is rotated together with the blades due to the water flow and electric power is generated due to the rotation of the rotary shaft.
Further, in a sterilizer of toilet boll flushing water disclosed in Japanese Patent Laid-open Publication 2000-27262, a flow passage is formed in the inside of an apparatus body, a rotary shaft whose rotating axis extends in the direction orthogonal to the direction of a water flow is rotatably provided in a midst of the flow passage, and blades are formed on an outer periphery of the rotary shaft in a state that the blades extend in the radial direction, and a power generator is connected to the rotary shaft.
Further, the rotary shaft is rotated together with the blades due to the water flow and electric power is generated due to the rotation of the rotary shaft.
However, in the conventional apparatus, the rotary shaft whose rotating axis extends in the direction orthogonal to the direction of the water flow is rotatably provided in the midst of the flow passage, and the blades are formed on the outer periphery of the rotary shaft in a state that the blades extend in the radial direction. That is, in the conventional apparatus, no clearances are formed between the rotary shaft and the blades.
Accordingly, water which impinges on distal end portions of the blades flows not only toward the outside than the distal ends of the blades but also toward proximal end portions of the blades. Here, water which flows toward the proximal end portions of the blades exhibits a trivial action to rotate the blades and rather exhibits an action which functions as the resistance against the rotation of the blades. That is, water which flows toward the proximal end portions of the blades impedes the rotation of the blades thus giving rise to a loss of amount of power generated by a power generator.
Further, the conventional apparatus adopts the structure in which the rotating shaft is mounted on the apparatus body and does not adopt the structure which allows the detachable mounting of the power generating unit on the apparatus body and hence, an operation to assemble a power generating mechanism such as the rotary shaft and the blades to the apparatus body becomes cumbersome and, at the same time, the maintenance operation of the power generating mechanism also becomes cumbersome.